How to pre-make sandwiches for next day

I am cooking weekly for my husband's company; about 12-16 people every week. I would like to make more sandwiches, such as the open-faced salmon sandwich on lettuce with tomatoes, avocado, etc. Any hints on how to keep the bread from getting soggy on those and other sandwiches? I make everything the night before because he takes them into his office early the next morning. Love any tips you might give me, much appreciated!